salt test for Hygrometer

AQUADGIO1200

Hey fellas.....i decided to see how accurate my Digital Hygrometer (madelaine), i filled up a liquor bottle cap with table salt and dropped in a few drops of bottled water, sealed it in a zip lock bag along with the Hygrometer and let it sit for 8 hours. My first reading was 72 & the second test was 71. Would bottled make a difference?? I ran out of distilled water......the Madelaine brand of hygrometer is not one that you can calibrate....pre-calibrated from factory. Maybe i should just remember that its +3 from the normal reading??

Lasabar